Reprinted by permission of the Regents of the University of California from:
Thorp, R. W. 1969. Systematics and ecology of bees of the subgenus Diandrena (Hymenoptera: Andrenidae). University of California Publications in Entomology 52: 1-146.
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This species is most closely related to A. anatolis and may be distinguished from that species by its darker facial pubescence, darker integument, and more deeply emarginate labral process.
The percentage of individuals with paler facial pubescence and lighter, more greenish integument increases in populations of this species the farther north they are found. Because of the preponderance of females with predominantly pale facial pubescence, the northern populations were originally thought to be only subspecifically distinct from A. anatolis. However, it has been subsequently determined in this study that these populations are part of a cline of color variation in A. eothina.
Andrena eothina and A. anatolis are treated here as distinct species because they occur sympatrically in Ventura County and because of ecological differences.
FEMALE. — Integument dark bluish with some greenish reflections; antenna uniformly dark brownish-black, clypeus with moderately large, subapical dark triangle with violaceous reflections, forewing with stigma dark brownish-black; pubescence dark, brownish except whitish on scutellum, metanotum, and metasomal terga 2 to 4, golden on metasomal tergum 5, orange-brown with dark brown tips on anal fimbria; facial fovea with sheen black, tomentum coppery-brown. Head moderately shiny, closely, moderately coarsely punctate with tessellate interspaces; clypeus, latero- and supra-clypeal areas with punctures separated by less than one diameter; facial fovea, extending from summit of eye to bottom of antennal base; eye slightly arcuate medially; antennae with segments 3 to 3 of flagellum as 11: 6: 5; labrum with process deeply emarginate, apices pointed and divergent (fig. 31); subgenal coronet moderately short, moderately well developed; gena tessellate-punctate, punctures moderately fine, close, separated by about one diameter, becoming coarse and sparse posteroventrally; pubescence of clypeus moderately long, sparse, suberect. Mesosoma dull, tessellate-punctate; pronotum moderately finely punctate with transversely tessellate interspaces, dorsolateral angle nearly right-angled with lateral fold, posterior margin of pronotum transverse; mesoscutum densely, moderately coarsely punctate, punctures separated by one diameter or less with tessellate interspaces, becoming duller and with punctures more nearly contiguous posteromedially with tessellations finer, denser, notaulus short, distinct; scutellum and metanotum moderately shiny, rugose-punctate with punctures contiguous; propodeum rugose-punctate with tessellate interspaces, enclosure with borders ill-defined, with longitudinal rugulae basally and transverse tessellations apically; episternum 2 coarsely, closely punctate with tessellate interspaces, anteriorly with dorsal edges of punctures elevated, tessellate, finely, sparsely punctate posteriorly; wing lightly infuscated, submarginals 1: 2 (30: 34), stigma : rest of marginal cell (15: 20), hind wing with jugal lobe narrow and without incision between it and vannal, reaching level of cu-v; posterior trochanter with long, curved, brownish, perfect floccus; tibial scopa long, loose, simple except for narrow band of finely branched hairs poste¬riorly, posterior hairs of scopa slightly more than twice as long as width of tibia at apex; pubescence of mesoscutum with many long dark and numerous short paler hairs intermixed. Metasoma. moderately shiny, tessellate, finely, shallowly punctate, punctures separated by 1 to 2 diameters; pubescence of first tergum moderately long, erect, of terga 2 to 4 short, suberect, with moderately indistinct apical hair bands on terga 2 and 3, more distinct and complete band on apex of tergum 4. Length 7.5 to 8 mm, forewing 5.5 to 6 mm.
MALE. — Integument bluish-gray with some greenish reflections on head; antenna uniformly dark brownish-black, clypeus with narrow subapical dark margin with violaceous reflections; forewing with stigma dark yellow-brown; pubescence pale, white except coppery-brown laterally on face, above and behind eye in narrow band. Head moderately shiny, tessellate, densely punctate; clypeus, latero- and supraclypeal areas with punctures contiguous; parocular depression short, linear, with violaceous reflections; eyes slightly convergent below; antenna with segments 1 to 3 of flagellum as 10:5:7; labrum with process short, moderately broad, deeply emarginate topically, strongly recurved (fig. 32); mandibles moderately long, decussate; gena moderately coarsely punctate, punctures separated by 1 to 2 diameters, with moderately shiny, tessellate interspaces; Mesosoma dull, tessellate-punctate; pronotum finely, sparsely punctate with transversely tessellate interspaces, dorsolateral angle right-angled with lateral fold, posterior margin of pronotum nearly transverse; mesoscutum moderately coarsely punctate with punctures separated by 1 to 2 diameters, notaulus short, distinct; scutellum and metanotum shinier with coarser, closer punctures, punctures separated by one diameter or less; propodeum moderately coarsely, closely, shallowly punctate with tessellate interspaces and more or less fine striae joining junctures giving rugose-punctate appearance, punctures separated by about one diameter, enclosure longitudinally rugulose basally, transversely tessellate apically; episternum 2 coarsely, closely punctate with tessellate interspaces, anteriorly with dorsal edges of punctures elevated, tessellate, finely, sparsely punctate posteriorly; wing pale, submarginals 1:2 (17:18) stigma : rest of marginal cell (12:18), hind wing with jugal lobe narrow and without incision between it and vannal, reaching level of cu-v; pubescence of mesoscutum long, moderately dense. Metasoma moderately shiny, moderately coarsely, shallowly punctate with tessellate interspaces; punctures separated by 1 to 2 diameters; pubescence moderately long, erect on first tergum, about half as long, erect on tergum 2, short, subdepressed on terga 3 to 5, with indication of apical hair bands on terga 2 to 5. Length 6 to 7 mm, forewing 5 to 5.5 mm.